The present invention relates generally to hay harvesting machines, commonly referred to as mower-conditioners, and, more particularly, to improvements in the biasing mechanism for urging the upper conditioning roll toward a position relative to the lower conditioning roll.
Mower-conditioners have been provided for the harvesting of hay for a number of years. A mower-conditioner severs standing crop material and conveys the severed crop material rearwardly into a conditioning mechanism without depositing the severed crop upon the ground. The conditioning mechanism has undertaken many forms; however, a preferred embodiment utilizes a pair of generally vertically disposed intermeshing rubber rolls to crimp and/or crush severed crop material passing therebetween. To permit the passage of a variable amount of crop material between the conditioning rolls, the upper conditioning roll is pivotally mounted for movement toward and away from the lower conditioning roll. A biasing mechanism is generally provided to urge the upper conditioning roll toward a position relative to the lower conditioning roll.
One embodiment of a biasing mechanism utilizes torsion bars to provide a biasing force to the structure pivotally mounting the ends of the upper conditioning roll. Each torsion bar is provided with a hexagonal cross-section at each end; however, manufacturing variances make it difficult to manufacture each torsion bar so that all four hexagonal cross-sectioned ends can be aligned without preloading pressure to one end of the roll. Presently, to attain equalized pressure exerted on each end of the upper conditioning roll, the flats of all four hexagonal cross-sections would have to be properly aligned. Because of these manufacturing variances and the assembly of the torsion bars in current pressure adjustment mechanisms, as well as other component variances, one torsion bar will often become displaced more than the other, resulting in unequal pressure being exerted on the transverse ends of the upper conditioning roll and, therefore, uneven conditioning of the crop material.